Analysis And Research Of Clearance-Leakage Interference On Flow Field Characteristics Of Balanced Twin-Screw Compressor

Compared with other types of compressors,twin-screw compressor moving parts are purely rotary,which operate at higher speed,higher efficiency and higher delivery rate.Therefore,it is widely used in petroleum,chemical,shipbuilding,metallurgy,environmental protection,clean energy and other industries.However,the working method of the twin-screw compressors currently used in the market is single-side suction and single-side discharge,so that the compression elements is subjected to a one-way axial force,which easily cause excessive wear of the supporting elements.As a result,unplanned downtime has caused huge economic losses and safety problems.For the purpose of improving the disadvantages of traditional twin-screw compressors,prolong the trouble-free operation time and promote industrial development,the research team had proposed a balanced twin-screw compressor which can eliminate the axial force of the rotor to the greatest degree,the in-depth analysis and research of its structure and performance will greatly promote the improvement of Chinese industrial equipment level.For the purpose of optimizing the performance of balanced twin-screw compressor,many researches have been conducted on balanced twin-screw compressor based on the basic theory of twin-screw compressors and fluid dynamics theory in this paper,including the analysis of geometric characteristics of the rotor,the fluid model correction,the improvement of the grid generation method,the analysis of internal flow field characteristics,the analysis of the discharge pressure pulsation and the analysis of the effect of clearance leakage.In this paper,the 2LGF125/21 screw compressor is took as the research object,the geometric parameters of the rotor are determined based on the XSRM profile and known working parameters.The geometric characteristics of the rotor are solved by SCORG,the data of interdental volume change with the rotation angle of the male rotor and the data of the meshing line of the male and female rotors were obtained.To solve the problem of difficulty and low precision in the fluid model construction and grid generation of the balanced twin-screw compressor working chamber caused by the existence of the small clearances,a method of constructing a working fluid model that can consider the real clearances of cavity and generating high-precision grids with SCORG is summarized.In order to verify the feasibility of the model and investigate the internal flow field characteristics of the balanced twin-screw compressor,the numerical simulation of the working process is carried on by CFX,and the distribution of pressure,velocity,density,and fluid trajectory in the internal flow field were obtained.For purpose of fully researching and predicting the influence of operating parameters on the discharge pressure pulsation of the balanced twin-screw compressor,the simulation of the balanced twin-screw compressor discharge process under five different operating conditions are carried on by CFX.The pressure pulsation curves at the discharge port under different operating conditions are comparative analyzed,the results show that the outlet pressure deviating from the design conditions will negatively affect the discharge pressure pulsation.Under the same outlet pressure,the discharge pressure pulsation increases with the increase of the rotor speed.Aiming at the influence of clearance leakage characteristics on the flow field dynamic characteristics of the balanced twin-screw compressor,based on the formation mechanism of clearance leakage,seven types of fluid models with different clearances were constructed.The CFD technology was used as the research methods to carry out the fluid dynamics simulation analysis on the seven fluid models.The effects of variations in interdental clearance,tip clearance,and discharge end face clearance on the pressure and velocity distribution of internal flow field and the pulsation of discharge pressure is obtained.The analysis results show that the interdental clearance has the greatest influence on the distribution of the physical parameters of the flow field,and the discharge end face clearance has the greatest influence on the pulsation of discharge pressure.The research results have important guiding significance for structural optimization,operating parameters optimization,work efficiency improvement,vibration reduction and noise reduction of balanced twin-screw compressors,and the results also provide important empirical data for the engineering practice of balanced twin-screw compressors.